noun
gloom; melancholy; pent-up frustration
Refers to a heavy, oppressive feeling of sadness or worry, often with a sense of accumulated frustration. Frequently used in the phrase 憂さ晴らし (distraction from gloom).
憂さを晴らすためにカラオケに行った。
I went to karaoke to shake off my gloom.
彼は酒で憂さをまぎらわそうとした。
He tried to drown his sorrows in alcohol.
憂鬱 is a more clinical or formal term for depression or melancholy, while 憂さ is a more everyday, emotional word for gloom or pent-up frustration.
憂さ晴らし is the common compound meaning 'distraction from gloom' or 'blowing off steam', directly derived from 憂さ.
Derived from the classical adjective 憂し (ushi, 'sad, gloomy'), with the nominalizing suffix さ. The exact historical development is uncertain.